Module 3: Typical Roadway Drainage

1
Module 3 Typical Roadway Drainage

• Where it goes in
• Where it comes out

Stormwater System Maintenance A 4-Part Workshop
Series
2
(Chart for illustrative purposes only, based on
Best Professional Judgment of Southern RI
Conservation District)
3
We will review Good Housekeeping

• Where stormwater enters our system
• Inspecting and maintaining catch basins
• Minimizing erosion of shoulders and ditches

• Where stormwater leaves our system
• Addressing scouring and excessive sedimentation
  at outfalls

4
We will

• Review the goals as written in the General Permit
• Clarify or expand as needed
• Review what we are doing now
• Review how we report our activities
• Look for ways to improve our effectiveness and/or
  efficiency

5
Inspecting Maintaining Catch Basins
6
OM Program

• Required Goal
• Procedures for implementing regular catch basin
  inspection cleaning program
• Inspect all annually, document
• Clean as necessary
• Coordinate with illicit discharge detection
• Increase inspections in problem areas
• May request lesser frequency after 2 years
  documentation

7
Inspect, Document
8
(No Transcript)
9
Locate system components
manhole
Catch basin
outlet
10
How often to inspect?

• All catch basins annually for at least 2
  consecutive years
• May request approval of lesser frequency based on
  documentation
• RIGL 45-61.1 at least once per year for those
  designated as prone to flooding or contributing
  significantly to storm water management problems

11
Maintain as necessary

• Remove trash
• Remove sediment when trap is 1/3 full
• Make necessary physical repairs
• Document activities and volumes

12
Our Catch Basin Procedures

• Maps
• Schedule
• Forms
• What to inspect
• Typical maintenance
• Database

13
Literature recommends

• Bring
• Maps
• Camera
• Inspection/maintenance forms
• Pens
• Rod, tape or probe to measure depths
• Prybar to lift grates
• Cellphone for emergencies

14
Inspect, Document

• Trash debris
• Estimate volume
• Sediment
• Measure depth
• Vegetation
• Note blockages

• Contamination
• Petroleum products
• Biohazards
• Structural integrity
• Nothing broken
• Pipes free-flowing
• Illicit connection

15
Estimating Sediment Volume

• Volume area X depth
• Area typically pipe size x 4 x 3.12
• Total sump depth typically pipe size x 4
• Sediment depth total sump depth distance from
  pipe invert to top of sediment

16
Infiltrating Catch Basins

• Dry wells
• No bottom and/or short lengths of pipe with no
  outlet
• Standing water indicates clogging

17
Safety Tips

• Wear appropriate safety equipment
• Use proper temporary traffic control
• Use care and proper equipment to lift grates
  covers
• Dont enter a catch basin without proper
  training, and another person nearby

18
Minimizing Erosion of Shoulders Ditches
19
OM Program

• Required Goal
• Procedures to minimize erosion of road side
  shoulders ditches by requiring stabilization
• Reduce velocity

20
(No Transcript)
21
Low Impact Development
22
Shoulder Problems
23
(No Transcript)
24
(No Transcript)
25
Size and velocity are important!
26
Rain Gardens Biofilters
NCSU-BAE
27
Our Procedures for Shoulders Ditches

• Maps, database
• Schedule
• Forms
• Typical maintenance

28
Safety Tips

• Wear appropriate safety equipment
• Use proper temporary traffic control
• Be properly trained and familiar with equipment
• Dont leave edge drop-offs unprotected overnight

29
Locate potential problem areas

• Steep slopes
• Weak vegetation
• Un-foreseen areas of concentrated flow
• Un-planned vehicle pull-offs

30
Shoulder Repair

• Scoured areas should be filled and compacted
• Remove sediment/sand buildup when gt3 higher than
  road

31
Select for salt tolerance, minimum maintenance
32
We dont want
Phragmites
Purple loosestrife
33
Ditch Maintenance

• Area of concentrated flow Freshwater Wetlands
  Permit
• Work only in driest time of year
• Short sections at a time
• Start at outlet end, wait for it to stabilize

34
Recommended Practices

• Remove sediment build-up when 3 deep (about
  every 5 years)
• Restore infiltration in bottom by ripping with
  disc or roto-tiller

35
Recommended Practices

• Seed mulch at the end of each day
• Install temporary check dams as needed
• If channel gullies persist
• size stone based on velocity, or
• Consider grade control structure

36
Any time youre out

• Note odors, sheen (illicit discharge)
• Watch impact of new curb cuts, culverts

37
Scouring, Excessive Sedimentation at Outfalls
38
OM Program

• Required Goal
• Procedures to identify and report annually on
  scouring/excessive sedimentation at outfalls
• Procedures to remediate upon notification

39
(No Transcript)
40
SECTION III.B Discharges Causing Scouring or
Excessive Sedimentation (Part IV.B.6.b.1.v)
41
(No Transcript)
42
Note source
43
Note source
44
Our Procedures at Outfalls

• Maps, database
• Inspection
• Forms
• Reports
• Maintenance
• Schedules
• Typical outfall maintenance
• Reports

45
Outlet Protection
46
Outfall extensions
Half-culvert
Flexible Downdrain
47
Remove sediments with care
48
Retrofit opportunities
49
Typical Roadway Drainage

• Traditional Purpose
• Remove runoff from the driving surface
• Good Housekeeping Purpose
• Provide multiple opportunities for pollutants to
  be separated from runoff

50
Stormwater System Maintenance Employee Training

• Brought to you by

This program was developed by the Southern Rhode
Island Conservation District in partnership with
the URI Cooperative Extension RI NEMO Program and
the Rhode Island T2 Center. Funding was provided
by the RI Department of Environmental Management
and the RI Department of Transportation under the
Phase II Stormwater Education and Outreach
Project.